#app .box {
  width: 3rem;
  height: 1.5rem;
  border: 1px solid black;
  position: relative;
  margin: 0.3rem auto;
}
#app .box .pic {
  width: 100%;
  height: 100%;
}
#app .box .left,
#app .box .right {
  position: absolute;
  background-color: #fff;
  width: 0.3rem;
  height: 0.5rem;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  text-align: center;
  line-height: 0.5rem;
  cursor: pointer;
}
#app .box .left:hover,
#app .box .right:hover {
  background-color: #ddd;
}
#app .box .right {
  left: auto;
  right: 0;
}
